Aloha all,

Replying to myself again.  I have only the faintest idea what I'm  
doing, but this patch appears to take care of the problem described  
earlier, where the optional argument to the LaTeX caption command was  
recycled if not replaced by a new optional argument.

The captions exported to LaTeX now can include or not the optional  
argument.  My org-mode document now exports both captions and entries  
in the list of figures correctly.

All the best,
Tom